Today I added the Pro Fill system to make servicing my batteries easier. No more using a flashlight and mirror or sticking [banging] my head in to try to see the water level. Hope it works as well as the reviews indicate. I did have to shorten the connecting tubes to fit my batteries. If the are too long the caps tend to pop out. Also, the instructions say install the tubing, then put red caps where you need them. Much easier to lay out the system and add the caps before you install the tubing. A lot fewer scraped knuckles!